Telephone-relay.



0. WEENEEEWOED. TELEPHONE RELAY.

APPLICATION FILED JULY 6, 1907.

a sums-sum 2.

. 4% U/Wkifflflflm/Iwdi Wlm fiss s; I V INVENTOR ATTORNEYS 'f/ 352; W 4 a? (7/ 34 Z7 2/ Z5) Z3 No. 881,360. A PATENTED MAR.10 ,1908..

G. W. UNDERWOOD.

TELEPHONE RELAY.

rrmouxou FILED JULY 6, f I A 1907 a sums-sum a.

- I 'ATTORNEY;

J VENTOR.

CHARLES W. UNDERWOOD, OF CROWLEY, LOUl'SlANA.

TELEPHONE-RELAY.

Specification of Letters Patent.

Application filed July 6, 1907.

Patented March 10, 1908.

Serial No. 382,475.

To all-whom it may concern:

Be it known that I, CnAnLEs W. Unnam- WOOD, a citizen of the United States, residing at Crowley, in the county of Acadia and State of Louisiana, have invented a new and useful 'lelepl1one-Relay, of which the following is a specification.

This invention has reference to improvements in telephone relays, whereby the electrical undulations corresponding to sound waves passing over a line and acting upon a telephone receiver will, instead of being converted into air vibrations, be converted into mechanical vibrations which, in turn, are caused to act upon a microphonic or loose contact transmitter element, whereby electrical. undulations are set up in a second circuit but with increased amplitude or strength, and these undulations, in turn, are either transformed into air vibrations at a distant telephonic receiver or are again converted into other electrical undulations, corresponding to the original undulations, in still a third circuit, and soon.

I The invention, while applicable to therelaying of telephonic currents which have become highly attenuated from long distance transmission, is not primarily designed for such purpose but is intended more particularly for the strengthening of telephonic cur rents at comparatively frequent intervals in a long line, so that the line conductors may be made of a material of less conductivity than copper, and far less costly. For instance, it is possible to transmit telephonic currents over long distances by means of iron Wire conductors by the use of relays constructed in accordance with my inven tion, which relays may be installed at frequent intervals in the line, say, at intervals of fifty or a hundred miles more or less. In this way, by augmenting the energy upon the line from time to time without materially ali'ccting the characteristics of the electrical undulations corresponding to the sound. waves as originally impressed upon the line, the original sounds uttered before the first transmitter will be received at the distant end of the line with. practically no diminu tion of force. Now, I have found by practical tests that by replacing the diapl'iragm of a telephone receiver by a light armature and supporting the latter by lightly stretched wires preferably radiating from a F circumscribed and centralized point of connection, made as small as possible, and by 1 connecting such armature to a telephonic transmitter element so that lhc impulses imparted to the armature by the telephonic receiver are caused to act upon the transmitter element, increased electrical energy may be thrown upon a second. line in the form of electrical undulations corresponding to all characteristics of the original undulations.

I have found by an extended series of tests that a diaphragm such as is used in a telephonic receiver or transmitter does not re spond to the impulses coming over the line with that degree of sensitiveness requisite for transferring to the microphonic element impulses of such magnitude as tothrow upon the second line impulses sulliciently augmented as to exceed the lll'lplllSeS at the rcceiver end of the first line. By supporting a small armature closely adjacent to the poles of the receiver magnet, upon either wires or thin, narrow, metallic ribbons and placing said wires or ribbons under critical longitudinal stress with their points of conrier midway between their ends, and with such points of connection centralized with relation to the magnetic field produced by the receiver magnet and preferably reduced to an area of very small proportions, l have found that there is a very marked increase in the effect upon the armaturo of the electrical undulations acting on the receiver, and this eiiect is sufficiently energetic to produce in the transmitter element a sulficient amplitude of movement to cause electrical undulations upon the second line far in excess of the undulations reaching the telephone receiver. an augmented or increased amount ofelectrical energy thrown upon the next succeeding line, it is possible to overcome the attenuating effects of comparatively high resist ance conductor wires, such as iron \RllGS, so that the electrical efl'ects upon each succeeding telephonic receiver may be practically all alike, since at each relay there is additional energy thrown upon the line, and resistance and other losses are thereby overcome.

find that by placing the armature of the receiver in magnetic equilibrium 1 addverv materially to the sensitiveness of the relay. This I do by the use of a permanent magnet in line nilh and facing the polar ends of the receiver magnet, and mountinganother arl nature in proper relation to the first al'lllfir nection with the armature or armature car-' Now, since at each relay there is ture and mechanically connected thereto, with both armatures axially connected at a circumscribed pointof connection with radially disposed wire or narrow ribbon sup ports under longitudinal stress, and all the parts so adjusted as to bring the armatures into magnetic equilibrium with relation to' sound waves, passin through the receiver currents, have a sensi ly greater effect upon the armature than when the latter is not In addition, there.

magnetically balanced. may be other tension wires disposed at right angles to the first-mentioned wires and put under such a degree of stress as v. ill prevent a movement of the armature or armatures un der the influence of shocks or jars to which the instrument may be subjected in use, so that the aXis of the armature acted upon by the receiver magnet may be maintained at the initially adjusted point of centralization with reference to the magnet poles.

The invention will be fully understood from the follow ing detailed description, taken in connection vith the accompanying draw ings forming part of this specification, in which,

Figure-1 is a plan view, with parts in scetion, of the improved relay arranged for the transmission of sound waves in both dire-- tions; Fig. 2 is a section through one of the relay elements upon a larger scale than shown in Fig. 1; Fig. 3 is a detail view showing the manner of supporting the receiver armature; and Fig. 4 is a diagram illustrating the introduction of a' relay between two outlying stations.

Referring to the drawings, there is shown a suitable base 1 upon which are erected two sets of'opposed standards 2---3 and 4-.-5. The standards-2-3 are joined by connecting bars 6 near their upper ends, and the standards 1-5 are similarly. joined. The bars 6 connecting the standards 2-3 are shown in Fig. 1, while the bars 6 connecting the standards 45 are shown in Fig. 2. Each standard is composed of two side members joined by a base plate 7 and a top bar 8.

Arranged centrally with relation to the side bars'ot each standard is a ring 9 having radial arms 10-11 so disposed that the arm 10 is secured to an car 12 formed on the top cross bar 8, while the arms 11 project in opposite directions from the ring 9 and are made fast to ears 13 formed on the side bars of the respective standard. The ring 9 is formed with an interior screw-thread which receives a bushing 14 carrying a permanent magnet 15 provided with soft iron pole pieces 16 on the ends'oi which are telephone receiver coils 17 The pole piecesIiB are 1 separated by a block 18 which carries terminal sockets 19 connected to the terminals of the coils 17 by conductors 20, and these sockets receive theterminal plugs 21 of flexible conductors 22, which, in turn, may be coupled up to the main line conductors of the telephone system.

In the structure forming the relay which constitutes the subject-matter of the present invention there,are two pairs -of opposed permanent maghets 15 with the supporting structures already described, but only one permanent magnet of each pair is supplied 1 with the receiver coils 17. l\ ow considering lbut one pair of ermanent magnets, say, those carried by t e standards 45, it Wlll be seen that the pole pieces of these two magnets face each other but are separated by a considerable distance. Adjacent to each magnet is a disk-shaped iron armature 23 having an. axial sleeve 24 on the face away from the polar end of the magnet, and these sleeves receive the ends of a connecting rod 25, preferably of insulating material such as wood or vulcanized fiber or vulcanized rubber, the length of the rod 25 being such that when the armature disks are properly mounted thereon they will be brought into very close relation to but will still be. out 'of contact with the polar extremities of the magnets. Projecting axially-from the ends of the rod 25 are pins or studs 26. Each of these studs is reduced at its free end to as small an area as may be, and there has secured. to it by a minute drop of solder or otherwise the middle point of a wire or narrow, thin band 27 of metal. The pins or studs 26 may or may not touch the center of the draphragm.

Let it be considered for the purposes of the following description that the part 27 is a wire, with the understanding, however, that a thin, narrow band is the equivalent of a wire and may be substituted therefor without materially affecting the operation of the device. Each end of the wire is carried to an adjusting screw 28 or 29, as the case may be. The screw 28 is tapped into a lug 30 projecting from the top cross bar 8, while the screw 29 is tapped into a lug 31 projecting from the base 7. It is immaterial for the purposes of the present invention how screws, and I have shown, merely by way of example, one way in which these wires may be fastened. As shown. in the drawings the ends of the wires'are formed into loops 32 through which may be passed pins 33, each engaging the end of a hollow sleeve 34 I passing through the bore of the screw and j also" receiving the corresponding end of the wire 27. This structure permits the'placing i of the wire under longitudinal strain or ten l sion without subjecting said ,wire to a twisting strain, although I have found in practice phpt a slight twisting of the wire is not harm- The sleeves 24 which carry the armature disks 23 are slotted longitudinally on opposite sides so that they may be slipped on to the ends of the rod 25 after the wire 27 has been fastened to the studs 26, and these hereinafter appear.

sleeves will offer no resistance to the movement of the wire with relation to the rod 25 when the latter is caused to reciprocate in the direction of its longitudinal axis, as will There are two Wires 27, one at each end of the rod 25, and there are therefore four screws 28 29, and each of these screws may be engaged b a clamp screw although but one suci screw is shown in the drawings, in Fig. 2. Now, by the proper manipulation of the screws 28 and 29 acting on each wire 27, the point. of connectionbetween the studs 26 and the wires 27, which point is central to'the armature disks 23, maybe brought into exact coincidence with the center of the magnetic field produced by the telephone receiver magnet and by the opposing magnet at the When this adjustother end of the rod 25. ment which is'at right angles to the direction of adjustment of the receiver magnets, is obtained. the wires 27 are put under longitudinal stress by the proper manipulation of the two screws 28 and 29 until a critical stress under .which the instrument will 0 crate to best advantage, is obtained. n addition to this, the magnets may by means ofthe screw bushing 14 be brought into such relation of their polar ends to the armatures 23 that these armatures, with the connecting rod 25, are brought into a state of magnetic equilibrium. Now, when electrical undulations corresponding to sound. waves are passed through the coils 17 the magneticarmature 23 at the other end of the rod 25.

Since the normal magnetic pull of the two' magnets is in equilibrium, there is practically no resistance to the movement of the armature 23 toward the telephone receiver magnet except that o'liered by thestress of the wires 27. I have found from actual tests that by making the connection of these wires at their central points of as small an area as possible, so as to localize or centralize these connections with reference to the armature disks, that the sensitiveiiess of the structure is greatly augmented.

' Fast uponone of the standards, say the standard 4 of the telephone receiver set I equilibrium-.

ing at their ends a bridging bracket 37 to the central portion of which is secured the microphonic elements 38 of an ordinary telephone transmitter. Since this micro phonic element may be of the usual type there is no need of describing it in detail. To the stem 39 of this element 38 there is secured an arm 40,fast on a sleeve 41 encircling the rod 25 and secured to thelatter for movement therewith. The microphonic element 38 is provided with a back stud 42, as is usual, and to this stud there is con nected a conductor 43 which may lead to a binding post 44 on the base -1, while the stem 39 is connected by a conducting strap 45 to an insulated binding post 46 fast on the bracket 37 and, in turn, connected by a conductor 47 to a binding post 48 upon the base 1.

It will be observed that the arrangement of-the microph'onic "element with relation to the telephonic receiver is such that when the pull of thereceiver magnet is augmented by an increased pulsation of current passing through the coils 17 and the armature 233 is therefore most.energetically actuated, the carbon particles in the microphonic element are subjected to a compression movement, while when the armature moves away from the magnet under the action of the tension wires 27, the movable part of the micro phonic element is then actuated in the direction of least resistance to its movement. Thus at all times the micrrmhonic element whenactuated in the direction in which it offers the greatest resistz-mce mechanically, is subjected to the strongest pull which the telephonic receiver is capable of exerting.

In order that the armatures 23 may not be subjected to lateral disturbances, other tension wires 49 under the action of adjusting screws 50 may be provided at right angles.

to the main tension wires 27, and these latter named wires 49 may be put only'undcr such strain as may-be found necessary to prevent such lateral disturbance. v

In each relay there are provided two telephone receivers, each with its opposing per manent magnet for establishing magnetic It is possible, however, to omit the opposing permanent magnet and so adjust the tension wires 27 as to prevent the constant pull of the magnet cz-rrrying the coils from bringing the armature into contact with the polar extremities of such mag: net. While such an arrangement is within the scope of my invention, still I iind the best results are obtained when the armatures are maintained in a state of magnetic equilibrium. I

Referring nowto Fig. 4, let it be assumed that electrical undulations corresponding to speech waves are coming over the line wires til-51. from a distant pointand pass through the telephone receiver cells 17 of the relay.

-' under consideration, are brackets 36 carry- 'lhecorrespending armatures 223 are set into vibration and actuate the microphonic element 38 under the control of this particular receiver included in 'the line 5151. The

microphonic element or transmitter 38 is in cluded in a circuit which also includes a battery 52 and the coarse wire coil 53 of a telephone induction coil, the fine wire coil 54 of however, that the listener at the further end of the system should desire to reply, so that the speaker at the first-named end of the system may hear the reply. For this purpose there is included in each relay a return circuit acting in the reverse order to the outgoing circuit. Referring again to the diagram of Fig. 4, it will be seen-that in the line conductors 55 there is included the receiver coils 17 of another telephonic receiver which may be mounted upon the same base-board as the receiver including the coils 17 connected up in the circuit of the line wires 51. The receiver-which is included in the line wires 55 acts upon another microphonic element or transmitter 38 in the circuit of which may be included a battery 52 and coarse wire coil 53 of a telephone induction coil, the fine wire coil 54 of which is included in the line wires 51. It will thus be seen that each relay therefore includes an outgoing unit and an incoming unit, so that conversation may be carried on in both directions as in the ordinary telephone systems. In order to prevent such mechanical resistance to the action of the instrument as may be offered by the air, the entire relay may be inclosed in an air-tight case 56 and the air-may be exhausted therefrom so that the moving parts will work in a vacuum and the air resistance to mechanical movement of these parts may be eliminated.

While the relay forming the subject of the present invention may be introduced in a .line having an ordinary telephone set at each end, so that electrical undulations which have become attenuated through lon distance transmission may be transforme into much more powerful undulations in a second circuit, dth a marked increase in volume or loudness and without substantial loss in clearness so that telephonic conversations may be held over greatly increased distances, still, it is the particular purpose of the present invention to relay the electrical impulses at romparatiy ely frequent intervals. By this means the electrical energy may be augmented to such an extent and at such frequent icall intervals that it is quite possible to use iron line conductors and thus effect a large saving in the cost of the installation of telephone lines.

In the foregoing descri tion emphasis has been laid upon the fact t at the connection between the wire 27- and the armature su port is of very limited area and central to t e said armature This I find to give the best results, but results far better than can be obtained with a diaphragm supporting the armature ,23, although not so good as with the structure hereinbefore described, may be obtained by connecting the wire 27 at points somewhat remote from the axial line of the rod 25, and these connections may be made even at the periphery of the armature 23, althou h, as before stated, the results are not as goo as when the connection is made at a oint localized to the center of the armature.

n-any event, the'wire or narrow band extending radially with relation to the armature 23 and su ported at its ends under initial 10 tudinal strain or stress, I find gives res ts far exceeding the results obtained lkyna diaphragm peri herally supported. I d that the stretche wire support for the armature is exceedingly sensitive to the slightest impulse due to the effect of telephonic currents passing through the coils of t e telephone receiver, and, consequently, the transmitter will throw upon the second circuit a faithful reproduction of the original impulses, which,

,however, are greatly augmented in said second circuit. The transmissional losses due to the action of a diaphragm, I find practically eliminated when the stretched wire support is used.

I cla1m:

1. In a telephone relay,-a telephone receiver magnet and coils,-a telephonic transmitter, an armature in operative relation to the telephone receiver magnet and mechanically connected to the transmitter element, and a wire support for the armature havin IN a localized central connection thereto, sai wire being under longitudinal strain or stress.

2. In a telephone relayfa telephone receiver'magnet and coils, another permanent magnet having its polar extremities facing but s aced from the polar extremities of the telepl ione receiver magnet, connected armatures in operative relation to the polar ends of the opposed magnets, and wire supports for the armatures having a localized central connection thereto and said wire being under initial longitudinal strain or stress.

3. In a telephone relay, a telephone re ceiver magnet and coils, a telephonic trans- 12 mitter, an armature in operative relation to the telephone receiver magnet, and mechanconnected to the transmitter element,

a wire support for the armature having a localized central connection thereto, and 13 magnet and for putting the wirefunder initial longitudinal strain or stress; and a telephonic transmitter mechanically connected to the armature.

.5. In a telephone relay,' .a-.-teleph0ne receiver magnet and coils, an armature in oper ative relation to the 'receiver magnet, awire support for the armature having a localized central connection thereto and under initial longitudinal strain or stress, a telephonic transmitter, and connections between the; armature andtransmitter so arran ed'that the-tran'smitte'rparts are moved in t e direction of compression when the receiver magnet is strengthened bythe passage of a current impulse. 4

6. In a telephone relay, a telephone re ceiver connected" up to a tele hone line, an armature under the control 0 said receiver, a wire support'for-the armature having a localized central connectionthereto and un-' der initial longitudinal stress or strain, a telephonic transmitter mechanically connected to said armature and included in a second telephonic line circuit, a tele )honic receiver connected up in the said secon line circuit, an

armature therefor, wire supports for said lastnanied armature, said supports having a localized central connection to the armature and being under initial longitudinal stress or i strain, another, telephonic transmitter me- ,chanically connected to said second armature, and electrical connections between said second transmitter and the first-named telephone line circuit.

int

7. In a telephone relay, a telephone receiver magnet and coils, an armature in operative relation to the magnet, a wire support for the armature having a localized central connectionthereto and arranged to beput' under initial longitudinal strain or stress,

other wire sup orts arran ed at substantially right ang es to the rst-named wire support and also connected to the armature e same manner as the first-named wire support, a telephonic transmitter, and mechanical connections between the armature and said transmitter.

.8. In a telephone relay, a telephone re ceiver magnet and coils, a telephonic transnutter, an armature in operative relation to the telephone receiver magnet and mechanically connected to the transmitter element,

and a support for thearmature dis osed rarelation to theaxisof t e armature, said support being of small cross-secdially wit tional area and. under initial longitudinal stress or strain.

9. In a telephone relay, a telephonereceiver magnet and coils, atelephonic transmitter, an armature in operative relation to the telephone receiver magnet and mechanically connected to the transmitter element,

,a support for the armature of small cross sectional area .(lis osed radially with relation to the axis of sai armature and under initial longitudinal stress orstrain, and a vacuum chamber inclosing the receiver, transmitter, armature, and armature support.

- 10, In a telephone relay, a telephone transmitter, a telephone receiver, and a tightly stretched support for the receiver armature having a connection of small area to said receiver, said connection bein centralized With relation to the magnetic i eld of the receiver. p

In testimonythat I- claim the foregoing as my own, I have hereto affixed my signature in thepresence of two witnesses.

, CHARLES W. UNDERWOOD.

Witnesses:

Ms. M. WALKER, WM. F. .SALTER. 

